U.S. patent application number 13/499188 was filed with the patent office on 2012-09-27 for system and method for maintaining air temperature within a building hvac system.
This patent application is currently assigned to CARRIER CORPORATION. Invention is credited to Michel Grabon, Yuhui Kuang, Dong Luo, Stella M. Oggianu, Shui Yuan.
Application Number | 20120245739 13/499188 |
Document ID | / |
Family ID | 43826863 |
Filed Date | 2012-09-27 |
United States Patent
Application |
20120245739 |
Kind Code |
A1 |
Grabon; Michel ; et
al. |
September 27, 2012 |
SYSTEM AND METHOD FOR MAINTAINING AIR TEMPERATURE WITHIN A BUILDING
HVAC SYSTEM
Abstract
A system and method for conditioning air within an air handling
system of a building is provided. The building has a hot water
source and a cold water source. The conditioning system includes at
least one heating-cooling unit connected to the air handling
system, a primary water storage device, at least one heat pump, and
a controller. The heating-cooling unit, which includes at least one
chilled beam, is operable to transfer heat into or out of air
passing within the air handling system of the building. The primary
water storage device is operable to store a volume of water within
a predetermined temperature range. The primary water storage device
is in communication with the hot water source and the cold water
source. The heat pump is connected to the primary water storage
device and the chilled beam. The controller is adapted to
selectively drive the heat pump to transfer heat between the
primary water storage device and the chilled beam. The controller
is also adapted to selectively control the system to transfer heat
into or out of the primary water storage device to maintain the
water within the primary storage device within the predetermined
temperature range.
Inventors: |
Grabon; Michel; (Bressolles,
FR) ; Yuan; Shui; (Simsbury, CT) ; Kuang;
Yuhui; (Shanghai, CN) ; Luo; Dong; (South
Windsor, CT) ; Oggianu; Stella M.; (West Hartford,
CT) |
Assignee: |
CARRIER CORPORATION
Farmington
CT
|
Family ID: |
43826863 |
Appl. No.: |
13/499188 |
Filed: |
September 29, 2010 |
PCT Filed: |
September 29, 2010 |
PCT NO: |
PCT/US10/50713 |
371 Date: |
June 11, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61246806 |
Sep 29, 2009 |
|
|
|
Current U.S.
Class: |
700/276 |
Current CPC
Class: |
F24D 5/04 20130101; F25B
2400/24 20130101; F24D 5/12 20130101; F25B 2400/06 20130101; Y02B
30/12 20130101; F24F 2203/02 20130101; F24F 3/08 20130101; F25B
13/00 20130101; F25B 29/003 20130101; F24H 6/00 20130101; F24H 4/04
20130101; Y02B 30/125 20180501; Y02B 30/13 20180501; F24D 19/1087
20130101; F25B 49/02 20130101 |
Class at
Publication: |
700/276 |
International
Class: |
G05D 23/00 20060101
G05D023/00 |
Claims
1. A system for conditioning air within an air handling system of a
building, which building has a hot water source and a cold water
source, the conditioning system comprising: at least one
heating-cooling unit connected to the air handling system, which
unit is operable to transfer heat into or out of air passing within
the air handling system of the building, and which unit includes at
least one chilled beam; a primary water storage device operable to
store a volume of water within a predetermined temperature range,
which primary water storage device is in communication with the hot
water source and the cold water source; at least one first heat
pump connected to the primary water storage device and the at least
one chilled beam of the heating-cooling unit; and a controller
adapted to selectively drive the first heat pump to transfer heat
between the primary water storage device and the chilled beam of
the heating-cooling unit, and adapted to selectively control the
system to transfer heat into or out of the primary water storage
device to maintain the water within the primary storage device
within the predetermined temperature range.
2. The system of claim 1, wherein the first heat pump is a
water-to-water heat pump.
3. The system of claim 1, further comprising an air-source heat
pump that is operable to transfer heat between the water within the
primary storage device and ambient air, wherein the controller is
adapted to control the transfer of heat between the water within
the primary storage device and ambient air.
4. The system of claim 1, wherein the controller is adapted to
operate a second heat pump to transfer heat from the hot water
source to the primary storage device to increase the temperature of
water disposed within the primary water storage device, and adapted
to selectively transfer heat from the primary storage device to the
cold water source to decrease the temperature of water disposed
within the primary water storage device.
5. The system of claim 4, wherein the cold water source is a
potable source of cold water within the building.
6. The system of claim 4, wherein the hot water source is a potable
source of hot water within the building.
7. The system of claim 1, further comprising a hot water storage
device and a second heat pump, wherein a second heat pump is
connected to the primary water storage device and the hot water
storage device, and the controller is adapted to selectively
operate the second heat pump to transfer heat from the hot water
storage device to the primary storage device to increase the
temperature of water disposed within the primary water storage
device.
8. The system of claim 7, further comprising a cold water storage
device and a third heat pump, wherein the third heat pump is
connected to the primary water storage device and the cold water
storage device, and the controller is adapted to selectively
operate the third heat pump to transfer heat from the primary water
storage device to the cold water storage device to decrease the
temperature of water disposed within the primary water storage
device.
9. The system of claim 1, wherein at least one of a heating-cooling
unit and at least one of the first heat pump are configured in a
modular unit disposed within the system.
10. The system of claim 9, wherein one or more modular units is
sized to fit within a ceiling space of a building.
11. A method for conditioning air within an air handling system of
a building, which building has a hot water source and a chilled
water source, the method comprising the steps of: transferring heat
into or out of air passing within the air handling system of the
building using at least one heating-cooling unit connected to the
air handling system, which heating-cooling unit includes at least
one chilled beam; storing a volume of water within a primary water
storage within a predeteiinined temperature range, which primary
water storage device is in communication with the hot water source
and the cold water source; transferring heat between the primary
water storage device and the chilled beam of the heating-cooling
unit; and transferring heat into or out of the primary water
storage device to maintain the water within the primary storage
device within the predetermined temperature range.
12. The method of claim 11, wherein a water-to-water heat pump
transfers heat between the primary water storage device and the
chilled beam of the heating-cooling unit.
13. The method of claim 11, further comprising the step of:
transferring heat between the water within the primary storage
device and ambient air using an air-source heat pump.
14. The method of claim 11, wherein the step of transferring heat
into or out of the primary water storage device to maintain the
water within the primary storage device within the predetermined
temperature range includes the steps of: selectively transferring
heat from the hot water source to the primary storage device using
a water-to-water heat pump to increase the temperature of water
disposed within the primary water storage device; or selectively
transferring heat from the primary storage device to the cold water
source to decrease the temperature of water disposed within the
primary water storage device.
15. The method of claim 14, wherein the hot water source is a
potable source of hot water within the building.
16. The method of claim 11, wherein the step of transferring heat
into or out of the primary water storage device to maintain the
water within the primary storage device within the predetermined
temperature range includes the steps of: selectively transferring
heat from a hot water storage device to the primary storage device
using a water-to-water heat pump to increase the temperature of
water disposed within the primary water storage device; or
selectively transferring heat from the primary storage device to a
cold water storage using a water-to-water heat pump to decrease the
temperature of water disposed within the primary water storage
device.
17. The method of claim 16, wherein the cold water storage device
is connected to the source of cold water within the building.
18. The method of claim 16, wherein the hot water storage device is
connected to the source of hot water within the building.
19. The method of claim 11, further includes providing a plurality
of heating-cooling units and a plurality of first heat pumps, which
heating-cooling units and first heat pumps are configured in
modular units disposed within the system; and wherein the step of
transferring heat into or out of air passing within the air
handling system of the building uses the modular units.
20. The method of claim 19, further comprising the step of
disposing one or more of the modular units within a ceiling space
of the building.
21. The method of claim 19, wherein the modular units are disposed
on a plurality of floors of the building and the step of
transferring heat into or out of air passing within the air
handling system is performed on a floor-by-floor basis.
Description
[0001] Applicant hereby claims priority benefits under 35 U.S.C.
.sctn.119(e) of U.S. Provisional Patent Application No. 61/246,806
filed Sep. 29, 2009, the disclosure of which is herein incorporated
by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Technical Field
[0003] The present method and system relate to methods and systems
for maintaining air temperature within a building in general, and
to methods and systems for maintaining air temperature within an
air handling system of a building in particular.
[0004] 2. Background Information
[0005] In large buildings, traditional air conditioning systems are
often centralized. Most centralized air conditioning systems
require space for machinery rooms (usually in a basement), which
rooms typically include installed chillers. Thermal energy residing
within the building is transferred to the outside of the building
via cooling towers located outside of the building. Alternatively,
air cooled chillers may be installed outside of the building. Fresh
air is treated by air handling units installed in one part of the
building and air is delivered to each floor by duct work which
requires large vertical conduits (between centralized air handling
equipment and each floor). This configuration occupies a lot of
space in a building and must conform to regulatory constraints
relating to fire safety (vertical ducts can potentially facilitate
fire propagation between floors).
[0006] Heating, ventilating, and air conditioning (HVAC) costs
represent a significant percentage of the energy costs required to
operate a building. Historically, chilled beam HVAC systems have
relied upon heating and cooling coils to add heat to, or take heat
out of the chilled beams. The use of heating and/or cooling coils
dedicated to the chilled beam HVAC system add to the cost of the
system and represent an energy cost during operation.
[0007] What is needed is an HVAC system, and method for operating
the same, that utilizes heating and cooling sources that have lower
installation and operating costs and have minimal system
requirements.
SUMMARY OF THE DISCLOSURE
[0008] According to one aspect of the present invention a system
for conditioning air within an air handling system of a building is
provided. The building has a hot water source and a cold water
source. The conditioning system includes at least one
heating-cooling unit connected to the air handling system, a
primary water storage device, at least one heat pump, and a
controller. The heating-cooling unit, which includes at least one
chilled beam and/or fan coil unit, is operable to transfer heat
into or out of air passing within the air handling system of the
building. The primary water storage device is operable to store a
volume of water within a predetermined temperature range. The
primary water storage device is in communication with the hot water
source and the cold water source. The heat pump is connected to the
primary water storage device and the chilled beam and/or fan coil
unit. The controller is adapted to selectively drive the heat pump
to transfer heat between the primary water storage device and the
chilled beam and/or fan coil unit. The controller is also adapted
to selectively control the system to transfer heat into or out of
the primary water storage device to maintain the water within the
primary storage device within the predetermined temperature
range.
[0009] According to another aspect of the present invention, a
method for conditioning air within an air handling system of a
building is provided. The building has a hot water source and a
chilled water source. The method comprises the steps of: a)
transferring heat into or out of air passing within the air
handling system of the building using at least one heating-cooling
unit connected to the air handling system, which heating-cooling
unit includes at least one chilled beam and/or fan coil unit; b)
storing a volume of water within a primary water storage device
within a predetermined temperature range, which primary water
storage device is in communication with the hot water source and
the cold water source; c) transferring heat between the primary
water storage device and the chilled beam and/or fan coil unit of
the heating-cooling unit; and d) transferring heat into or out of
the primary water storage device to maintain the water within the
primary storage device within the predetermined temperature
range.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a diagrammatic illustration of an air handling
system in combination with the present system for conditioning
air.
[0011] FIG. 2 is a diagrammatic illustration of the present system
for conditioning air.
[0012] FIG. 3 is a diagrammatic illustration of a heat pump
embodiment.
[0013] FIG. 4 is a diagrammatic illustration of a heat pump
embodiment in a cooling mode configuration.
[0014] FIG. 5 is a diagrammatic illustration of a heat pump
embodiment in a heating mode configuration.
DETAILED DESCRIPTION OF THE INVENTION
[0015] Referring to FIGS. 1 and 2, the present system for
conditioning air within an air handling system 10 of a building
includes one or more heating-cooling units 12 connected to the air
handling system 10, a primary storage device 14, and one or more
heat pumps 16 connected to the primary water storage device 14 and
the heating-cooling unit 12. The air handling system 10 can be
operated (e.g., in cooling mode) in a such way that air entering
the building is dry enough to allow a chilled beam or fan coil unit
to operate without moisture condensation. In other words, the air
handling system is taking care of the latent load of the air while
the chilled beam or fan coil unit is addressing the sensible heat
of the air.
[0016] Referring to FIG. 1, the air handling system 10 is operable
to cycle air through the building. Air is returned from the
building ("return air" 18) and into the engagement with the
heating-cooling unit 12. Air conditioned by a heating-cooling unit
12 is supplied to the building ("supply air" 20) after being
heated, cooled, or otherwise conditioned. FIG. 1 diagrammatically
illustrates flexible ducts and water piping going out to the
heating-cooling units 12 to illustrate the various units 12 that
may be placed around the entire building. In some embodiments, the
air handling system 10 is configured on a floor by floor basis
within multi-floor buildings, where the air handling system for
each floor may function independently of other floors. In many
instances, the air handling system 10 includes structure (e.g., fan
23 and conduit 25) for drawing fresh outside air 22 into the
building, structure 24 for conditioning the moisture content of the
air for use in the building (e.g., enthalpy wheel, etc.), and
structure (e.g., fan 27 and conduit 29) for exhausting building air
26 to the outside. The present invention is operable with a variety
of different air handling systems and is not, therefore, limited to
any particular air handling system.
[0017] Referring to FIG. 2, each heating-cooling unit 12 includes
one or more chilled beams 28 or fan coil units. For ease of
description, the term "chilled beam 28" as used herein shall mean
chilled beams and/or fan coil units, unless specifically indicated
otherwise. The heating-cooling units 12 may be deployed in a
plurality of zones disposed throughout the building. Each chilled
beam 28 has a water loop having an inlet and an exit to allow the
passage of water therethrough, and either has an air inlet and an
air exit to allow the passage of air relative to the chilled beam
28, or is disposed within a duct through which supply air is
directed. The heating-cooling units 12 may be passive and relay a
flow of air from the air handling unit 10 into the zone, or they
may be active units that utilize air flow from the handling unit
and/or a local means for passing air relative to the chilled beams
28; e.g., a fan. The present system and method are not limited to
any particular chilled beam 28 configuration.
[0018] Referring to FIG. 2, the primary storage device 14 is a
container that contains a volume of water within a predetermined
temperature range. The volume capacity of the primary storage
device 14 is based on the needs of the building (e.g., expected
maximum heating and cooling requirements). In most applications,
water stored in the primary storage device 14 is maintained in the
predetermined range of about 16-32.degree. C., and at a pressure of
about 2-3 bars, which temperature and pressure levels are within
the range of water temperatures and pressures typically found
within commercial buildings. Consequently, the primary storage
device 14 is designed to handle water at the aforesaid temperatures
and pressures. Water temperature in the system is low enough to
allow each individual heat pump to operate with relatively low
condensing temperature in a cooling mode. In particular, the water
temperature in the system may be low enough to permit the use of
carbon dioxide (CO.sub.2) refrigerant based reversible heat pumps,
which heat pumps can operate below critical point most of the time.
In such a mode, the efficiencies of the CO.sub.2 heat pump can be
significantly increased. The present invention is not, however,
limited to using CO.sub.2 type heat pumps, although such heat pumps
can be used in a very efficient way.
[0019] Referring to FIGS. 2-5, the one or more heat pumps 16 used
to transfer heat between the primary storage device 14 and the
heating-cooling units 12 are not limited to any particular type of
heat pump. In one embodiment (see FIG. 3), the heat pump 16 is a
water-to-water heat pump that includes a heat exchanger 29 and a
pair of pumps 31, 33 (e.g., variable speed reversible pumps). A
first pump 31 is dedicated to moving water through a chilled beam
closed loop, and a second pump 33 is dedicated to moving water
through a primary storage device closed loop. The heat exchanger 29
provides the interface between the two loops.
[0020] Another example of an acceptable water-to-water heat pump is
shown in FIGS. 4 and 5. FIG. 4 illustrates a water-to-water heat
pump 16 in a heating mode configuration, and FIG. 5 illustrates a
water-to-water heat pump 16 in a cooling mode configuration. Each
configuration includes a variable speed compressor 30 (or a fixed
speed compressor), an expansion valve 32, a pair of heat exchangers
34, 36, a four-way valve 38, and a pair of water pumps 40, 42. The
variable speed compressor 30, the expansion valve 32, and the heat
exchangers 34, 36 are connected to one another by lines that
contain a working fluid (e.g., refrigerant such as CO.sub.2). The
four-way valve 38 allows the heat pump 16 to operate in a heating
mode or in a cooling mode. One of the water pumps 40 circulates
water through a chilled beam closed loop which passes through one
of the heat exchangers 34, and the other water pump 42 circulates
water through a primary storage device closed loop which passes
through the other heat exchanger 36. The above described heat pump
16 embodiments are examples of acceptable heat pumps, and the
present system is not limited to using these embodiments.
[0021] Now referring to FIG. 2, in some embodiments the primary
storage device 14 is connected to an air-source heat pump 44 that
operates to maintain the primary storage device 14 within the
predetermined temperature range. When the temperature of the water
within the primary storage device 14 exceeds the predetermined
temperature range, the air-source heat pump 44 can be used to
extract the heat from primary storage device 14 and transfer it to
an ambient air source (e.g., outside air), provided the ambient air
source is at a lower temperature. Conversely, if the ambient air
source is at a temperature higher than the water within the primary
storage device 14, the air-source heat pump 44 can be used to add
heat to the water within the primary storage device 14. In some
embodiments, the air-source heat pump 44 includes a reversible
variable speed drive pump that can be used to provide a variety of
different water flow rates, and can be run in cooling or heating
mode. Acceptable air-source heat pumps 44 are known in the industry
and the specific type of air-source heat pump suitable for a
particular application will depend upon the requirements of that
application. In some applications, one or more air-source heat pump
44 can be placed outside of the building. In such outdoor
applications, materials such as propane can be safely used as a
refrigerant. Combinations of indoor heat pumps 44 (e.g., CO.sub.2)
and outdoor heat pumps 44 (e.g., propane) can be used.
[0022] The primary storage device 14 is in communication with a
cold water source disposed within the building. In some
embodiments, a heat pump 16A (e.g., like those described above)
connects a cold water storage device 46 to the primary storage
device 14. The cold water storage device 46 is filled using a
building cold water source and may, for example be filled with
fresh water that can be subsequently used for flushing toilets. The
volume capacity of the cold water storage device 46 is based on the
needs of the building (e.g., expected maximum heating cooling and
cooling requirements). In most applications, water stored in the
cold water storage device 46 is maintained in the range of about
16-32.degree. C., and at a pressure of about 2-3 bars, which
pressure level is within the range of water pressures typically
found within commercial buildings. Consequently, the cold water
storage device 46 is designed to handle water at the aforesaid
temperatures and pressures.
[0023] The system 10 is designed to provide both cooling and
heating. In situations where a majority of zones within the
building require cooling, the system water will have tendency to
increase its temperature. Under these circumstances, other cooling
sources may be used (in a cooling mode) to transfer heat away from
the main loop of the system to, for example, the water which is
used to flush toilets. A means that can be used to transfer the
energy in these instances is a water to water heat pump. The
aforesaid source of cooling energy is limited, so if necessary an
air cooled heat pump 44 can also be used to cool the main loop of
the system.
[0024] The primary storage device 14 is also connected to a hot
water source disposed within the building. In some embodiments, a
heat pump 16B connects a hot water storage device 48 to the primary
storage device 14. The hot water storage device 48 is filled using
a hot water source disposed in the building. The volume capacity of
the hot water storage device 48 is based on the needs of the
building (e.g., expected maximum heating cooling and cooling
requirements). In most applications, water stored in the hot water
storage device 48 is maintained in the range of about 50-70.degree.
C., and at a pressure of about 2-3 bars, which pressure level is
within the range of water pressures typically found within
commercial buildings. Consequently, the hot water storage device 48
is designed to handle water at the aforesaid temperatures and
pressures.
[0025] In situations where a majority of zones within the building
require heating, the water temperature within the main loop of the
system has a tendency to decrease. In such cases, other heating
sources may be used to compensate main loop water temperature drop.
Under these circumstances, other heating sources may be used (in a
heating mode) to transfer heat to the main loop of the system from,
for example, relatively high temperature sanitary water used in the
building. A means that can be used to transfer the energy in these
instances is a water to water heat pump. If there is not enough
energy in sanitary water to compensate for heating needs of the
floor, an air to water heat pump can be used to add additional
energy to the main water loop.
[0026] In a case when some of the zones require cooling and some of
the zones require heating, a situation may occur where the main
water loop remains in a constant temperature and in this case no
external cooling or heating is required. In these instances, the
traditional solution is to cool a part of the building, and to heat
a part of the building. Heating and cooling the building requires
large amounts of external energy. Using the present system, the
energy from one zone can be transferred to another zone, thereby
resulting in a significant savings in energy.
[0027] The system includes a controller 50 that is adapted to
provide control functions including: a) selectively driving one or
more heat pumps 16 to transfer heat between the primary storage
device 14 and the one or more chilled beams 28 of the
heating-cooling unit 12; and b) selectively controlling the system
to transfer heat into or out of the primary storage device 14 to
maintain the water within the primary storage device 14 within a
predetermined temperature range; e.g., by controlling the heat
pumps 16A, 16B and valves associated with the cold water storage
device 46 and the hot water storage device 48. Thermal sensors
disposed throughout the system can be used to provide input into
the controller 50 regarding the need to transfer heat into or out
of the primary storage device 14, and into and out of the cold and
hot water storage devices 46, 48 as will be explained below.
[0028] In those system embodiments that include an air-source heat
pump 44, the controller 50 is adapted to control the transfer of
heat between the water within the primary storage device 14 and
ambient air.
[0029] In those system embodiments that include a hot water storage
device 48, the controller 50 is adapted to selectively control
transfer of heat from the hot water storage device 48 to the
primary storage device 14 via a heat pump 16B to increase the
temperature of water disposed within the primary storage device 14.
In those system embodiments that include a cold water storage
device 46, the controller 50 is adapted to selectively control
transfer of heat to the cold water storage device 46 from the
primary storage device 14 via a heat pump 16A to decrease the
temperature of water disposed within the primary storage device
14.
[0030] The controller 50 may include a single processor programmed
(or having equivalent control hardware) to control the functions of
the working fluid hardware (e.g., heat pumps, valves, etc.)
associated with the embodiments described above. Alternatively, the
controller 50 may collectively include a plurality of processors
that are programmed (or have equivalent control hardware) to
collectively control the functions of the working fluid hardware;
e.g., a system controller in communication with processors disposed
in heat pumps 16, automated valves, etc.
[0031] In the operation of the present system, the primary storage
device 14 has a temperature range defined by an upper temperature
limit (Tpsdu) and a lower temperature limit (Tpsdl). In summer
months when the cooling requirements are greater, the temperature
of the primary storage device is maintained no higher than the
upper temperature limit (Tpsdu), while in the winter months when
heating requirements are greater, the temperature of the primary
storage device is maintained no lower than the lower temperature
limit (Tpsdl).
[0032] In those embodiments utilizing an air-source heat pump 44,
if the temperature of the water within the primary storage device
14 is above its upper limit (Tpsdu), and the ambient air
temperature is lower than the upper temperature limit (Tpsdu) for a
given period of time, then the air-source heat pump 44 can be
operated by the controller 50 to transfer heat from the water
within the primary storage device 14 to the ambient air. Likewise,
if the temperature of the water within the primary storage device
14 is below its lower limit (Tpsdl) and the ambient air temperature
is higher than the lower limit (Tpsdl) for a given period of time,
then the air-source heat pump 44 can be operated by the controller
50 to transfer heat from the ambient air to the water within the
primary storage device 14. If the cooling or heating requirements
cannot be met by the air-source heat pump 44 for a given period of
time, the additional requirements of the system can be met by
utilizing the cold water storage device 46 or the hot water storage
device 48 within the building.
[0033] In those system embodiments that include a cold water
storage device 46, the controller 50 is used to maintain cold water
(e.g., toilet flush water) within the cold water storage device 46
at a temperature that is cooler than Tpsdu, and preferably cooler
than Tpsdl. Automated valves connected to a building cold water
source can be controlled to add and remove water from the cold
water storage device 46 as necessary. If the temperature of the
water within the primary storage device 14 exceeds its upper
temperature limit (Tpsdu) for a given period of time, then the
controller 50 is adapted to transfer heat away from the primary
storage device 14 and to the cold water storage device 46 through
one or more heat pumps 16A. Once the temperature of the water
within the primary storage device 14 is back within the acceptable
temperature range, the controller 50 halts heat transfer via the
heat pumps 16A.
[0034] In those system embodiments that include a hot water storage
device 48, the controller 50 is used to maintain hot water within
the hot water storage device 48 at a temperature that is hotter
than Tpsdl, and preferably hotter than Tpsdu. Automated valves
connected to a building hot water source can be controlled to add
and remove water from the hot water storage device 48 as necessary.
If the temperature of the water within the primary storage device
14 falls below its lower temperature limit (Tpsdl) for a given
period of time, then the controller 50 is adapted to transfer heat
to the primary storage device 14 and away from the hot water
storage device 48 through one or more heat pumps 16B. Once the
temperature of the water within the primary storage device 14 is
back within the acceptable temperature range, the controller 50
halts heat transfer via the heat pumps 16B.
[0035] In those system embodiments that utilize a water-to-water
heat pump 16 as is shown in FIGS. 4 and 5, the controller 50 is
adapted to control operation of the heat pump 16 including
operation of the variable speed compressor 30 and the four-way
valve 38. For example, in the heating mode configuration shown in
FIG. 5, the four-way valve 38 is operated to direct the working
fluid exiting the compressor 30 to the heat exchanger 34 in
communication with the chilled beam closed loop, where heat from
the working fluid is transferred to the water within the chilled
beam loop via the heat exchanger 34. The working fluid exits the
heat exchanger 34 and enters the expansion valve 32. From the
expansion valve 32, the working fluid can either go to the heat
exchanger 36 in communication with the primary storage device
closed loop or can bypass that heat exchanger 36 and can go
directly back to the variable speed compressor 30. Heat from the
water within the primary storage device loop is transferred to the
working fluid as it passes through the heat exchanger 36. As a
result of the cycle, the heat pump 16 transfers heat from the
primary storage device 14 ultimately to the chilled beam 28, which
in turn increases the temperature of the air within the HVAC system
zone.
[0036] In the cooling mode configuration shown in FIG. 4, the
four-way valve 38 is operated to direct the working fluid exiting
the compressor 30 to the heat exchanger 36 in communication with
the primary storage device closed loop, where heat from the working
fluid is transferred to the water within the primary storage device
loop via the heat exchanger 36. The working fluid exits the heat
exchanger 36 and enters the expansion valve 32. From the expansion
valve 32, the working fluid goes to the heat exchanger 34 in
communication with the chilled beam closed loop. Heat from the
water within the chilled beam closed loop can be transferred to the
working fluid as it passes through the heat exchanger 34. As a
result of the cycle, the heat pump 16 transfers heat to the primary
storage device 14 and ultimately away from the chilled beam 28,
which in turn decreases the temperature of the air within the HVAC
system zone.
[0037] While various embodiments of the system and method for
maintaining air temperature within a building HVAC system have been
disclosed, it will be apparent to those of ordinary skill in the
art that many more embodiments and implementations are possible
within the scope of the method. For example, the present system has
the ability to remove heat from a first zone of the building and
transfer that heat to the primary storage device 14. If other zones
of the building require heat input, the present system can utilize
heat removed from certain zones to add heat to other zones via the
primary storage device 14.
[0038] Individual water-to-water reversible heat pump and
associated air delivery systems (which deliver the air to each
chilled beam or fan coil unit) are typically sized to fit above the
false ceiling on the particular floor where they are located. It is
important to note that in most buildings the available space above
a false ceiling has a tendency to be less above the office areas
than elsewhere, because of desire to optimize the work space of the
occupants. For example, in many buildings the floor to floor
distance is approximately 3 meters and the floor to ceiling
distance is approximately 2.5-2.75 meters. That leaves 0.5 to 0.25
meters of space above the false ceiling. This relatively confined
space is used to house all HVAC ductworks, piping, and
electrical/communication wiring. In many instances, this space is
not big enough to accommodate a reversible water-to-water heat pump
and an associated air delivery system. However, above bathroom
facilities, the space above the false ceiling is often larger;
e.g., approximately 1.0 meter.
[0039] Using the present system, however, the system can be
implemented in a modular manner where a reversible water-to-water
heat pump and an appropriate air delivery system (e.g., configured
as a modular unit) can be placed above each toilet within a
restroom within the building. In building standards, the number of
toilets is proportional to the occupant number (usually one toilet
for ten people). Under the present system, the physical size of a
water-to-water heat pump and air delivery systems as well as their
capacity (around 2 kW) can be selected in such a way that the
single "module" can be placed in a space above a single toilet and
provide comfort (cooling and heating) to ten people. The number of
modules can be increased with the number of toilets. In this
embodiment, the modular HVAC equipment is installed in a space
(e.g., above the toilet) which is otherwise not used. It also means
that it is easy to service the equipment without entering the
office space. Packaging the equipment as a modular unit is
facilitated because toilet sizes are typically standardized and the
number of toilets per building is proportional to the number of the
people in a floor. The present system can be tailored to the number
of people within the building without need for a specific machinery
room.
[0040] Air-to-water heat pumps (to maintain water loop temperature
at a desired temperature level as described above), as well as
fresh air handling equipment (e.g., air-to-water heat pump, energy
recovery device etc.) can also be placed inside the building (on
the same floor) in a specific room or if space is available in a
duct. Under the present system, therefore, the air conditioning
requirements of the building can be addressed on a floor-by-floor
basis (including fresh air). Under the present system, there is
limited or no need for vertical ducting in a building (an issue for
fire protection requirements), and the need for a central machinery
room is avoided. Consequently, the cost and space requirements
associated vertical ducting and a central machinery room are
avoided.
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